Spark plasma sintering of MgAl2O4-LaCr0.5Mn0.5O3 composite thermistor ceramics and a comparison investigation with conventional sintering

摘要

The microstructure and negative temperature coefficient (NTC) electrical properties of the MgAl2O4-LaCr0.5Mn0.5O3 composite ceramics prepared by spark plasma sintering (SPS) were investigated. The effects of SPS and conventional sintering (CS) on electrical properties and high temperature aging characteristics of 0.6MgAl2O4-0.4LaCr(0.5)Mn(0.5)O(3) ceramics were comparatively studied. X-ray diffraction (XRD) results showed both SPS- and CS-sintered ceramics were indexed to be cubic spinel MgAl2O4 phase and orthorhombic perovskite LaCr0.5Mn0.5O3 phase isomorphic to LaCrO3. Microstructural study reveled that SPS- sintered specimens had a higher relative density more than 96%. The electrical properties of the SPS- sintered NTC thermistors could be adjusted by changing MgAl2O4 content and sintering temperature. The SPS- sintered samples possessed a higher resistivity than that from conventionally sintered ceramics. The reasons for the increase of resistivity in the SPS- sintered samples, and the aging mechanism of the thermistor ceramics were investigated through applying the defect chemistry theory. (C) 2016 Elsevier B.V. All rights reserved.